The present invention generally relates to the upgrading of heavy oils and bitumens. More particularly, the present invention relates to a process for the upgrading of heavy oils and bitumens including one or more of the steps of production, desalting, dewatering, fractionation, solvent extraction, delayed coking, thermal cracking, fluid catalytic cracking and hydrotreating and/or hydrocracking to produce synthetic crude and/or naphtha, distillate and gas oil streams.
Refiners continue to seek improved methods for processing and converting heavy crude oil resources into more useful oils and end products. The heavier crudes, which can include bitumens, bitumens from tar sands, and other heavy oils, pose processing problems due to the presence of salts, metals, and organic acids. Bitumens and heavy oils are extremely viscous, resulting in problems in transporting the raw materials by traditional means. Heavy oils and bitumens often must be maintained at elevated temperatures to remain flowable, and/or mixed with a lighter hydrocarbon diluent for pipeline transportation. The diluent can be expensive and additional cost is normally incurred in transporting it to the location where production is occurring.
Additionally, natural occurring water in the oils, commonly known as produced water, contains salts. This water is in some processes vaporized to meet pipeline specifications for water content. Salts are thus left in the oil and then transported with the heavy oil or bitumen or with the solvent diluted heavy oil or bitumen.
FIG. 1 illustrates one of the process schemes for the processing of heavy oil or bitumen to convert into and recover useful hydrocarbon products. A heavy crude oil or bitumen feed 10 produced from a well, by an in-situ production method such as steam assisted gravity drainage (SAGD) or by a mining operation, can be mixed with a diluent to keep the mixture viscosity in a desired range for transport to a refinery or other facility for processing, and can also include water, salts, metals, silt, etc. Total feed 10 is ideally first processed to remove the water and salt from the hydrocarbons in desalter 12; the water and salt can be recovered via stream 14.
The hydrocarbons can be recovered in stream 16 and fed to crude or atmospheric distillation unit 18 to recover the diluent 20 and to obtain straight run naphtha, distillates, gas oil, and the like, recovered in stream 22. Diluent 20 can be recovered and returned to heavy oil or bitumen production or mining facilities via a pipeline. The atmospheric tower bottoms (ATB) residue 24 is usually further processed to increase the yield of the more valuable products, e.g. naphtha, distillates and gas oil. The ATB residue 24 may contain a large proportion of hydrocarbons boiling above 565° C. (1050° F.), as well as nitrogen, sulfur, and organometallic compounds, and Conradson carbon residue (CCR), and can be difficult to process. Frequently, a vacuum distillation tower 26 is employed to recover additional vacuum gas oil 28 from the ATB residue 24. The vacuum tower bottoms (VTB) residue 30 is even more concentrated in high-boiling hydrocarbons, e.g. normally boiling at greater than 565° C. (1050° F.), as well as CCR, sulfur, nitrogen and organometallic compounds.
In typical refinery processing with a vacuum distillation tower 26, the VTB residue 30 (and/or the ATB residue 24) can be fed to solvent deasphalting 32 (SDA). The solvent deasphalting 32 contacts the residue with propane, butane, pentane, hexane, or a combination thereof, or a like solvent (at either subcritical or supercritical conditions, e.g. residuum oil supercritical extraction or ROSE®; other SDA processes can include DEMEX and SOLVAHL, or conventional solvent deasphalting) to separate the asphaltenes 34 from deasphalted oil (DAO) 36 (and/or resins). The DAO 36 has lower levels of CCR, sulfur, nitrogen, and metals than the atmospheric resid/vacuum resid feed since these constituents are disproportionately retained with the asphaltenes 34.
The products 22, 28 obtained from the atmospheric tower 18 and vacuum tower 26, as well as DAO 36 from the solvent deasphalting 32, can be combined to form distillate stream 38. Distillate stream 38 or the individual product streams 22, 28, 36 are usually further processed to upgrade the hydrocarbons and remove additional nitrogen and sulfur in order to facilitate processing in catalytic cracking units, hydrotreating and hydrocracking units of any type, and the like, without prematurely poisoning their catalysts.
The typical FIG. 1 process for the separation and upgrading of heavy oil or bitumen feed into useful products involves several processing steps and can require a substantial capital investment. Additionally, the bitumen or heavy oil feed can include acidic species. Any acid in the bitumen or heavy oil feed can also require the use of expensive metallurgy in fractionation equipment usually operating above 232° C. (450° F.).
In U.S. Pat. No. 4,875,998, Rendall discloses the extraction of bitumen oils from tar-sands with hot water. Other water or solvent extraction processes are disclosed in U.S. Pat. No. 4,160,718 to Rendall; U.S. Pat. No. 4,347,118 to Funk, et al.; U.S. Pat. No. 3,925,189 to Wicks, III; and U.S. Pat. No. 4,424,112 to Rendall.
Other representative references directed to the production of crude petroleum from tar sands include Canadian Patent Application 2,069,515 by Kovalsky; U.S. Pat. No. 5,046,559 to Glandt; U.S. Pat. No. 5,318,124 to Ong et al; U.S. Pat. No. 5,215,146 to Sanchez; and Good, “Shell/Aostra Peace River Horizontal Well Demonstration Project,” 6th UNITAR Conference on Heavy Crude and Tar Sands (1995).
Solvent extraction of the residuum oil has been known since the 1930's, as previously described in U.S. Pat. No. 2,940,920, to Garwin. Other representative solvent deasphalting techniques using supercritical solvent conditions are described, for example, in publications such as Northup et al., “Advances in Solvent Deasphalting Technology,” presented at the 1996 NPRA Annual Meeting, San Antonio, Tex., Mar. 17-19, 1996, and Nelson et al., “ROSE®: The Energy-Efficient, Bottom-of-the-Barrel Alternative,” presented at the 1985 Spring AlChE Meeting, Houston, Tex., Mar. 24-25, 1985, all of which are incorporated herein by reference. Improved techniques in solvent extraction have been disclosed in U.S. Pat. No. 5,843,303 to Ganeshan. U.S. Pat. No. 6,357,526 discloses a process and system which integrates on-site heavy oil or bitumen upgrading and energy recovery for steam production with steam-assisted gravity drainage (SAGD) production of the heavy oil or bitumen which is maintained at elevated temperature for pumping to the upgrading unit.